


A Case of Magic

by Twinklingbright



Category: Harry Potter - J. K. Rowling, Sherlock (TV)
Genre: Crossover
Language: English
Status: In-Progress
Published: 2016-05-05
Updated: 2016-05-16
Packaged: 2018-06-06 13:04:06
Rating: General Audiences
Warnings: No Archive Warnings Apply
Chapters: 2
Words: 3,326
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/6755128
Author URL: https://archiveofourown.org/users/Twinklingbright/pseuds/Twinklingbright
Summary: <blockquote class="userstuff">
              <p>Sirius Black is reckless. Sherlock Holmes is bored. Great minds think alike.<br/>So what happens when the wrongly accused Marauder decides to ignore the Statute of Secrecy and to ask the Consulting Detective for help?</p>
            </blockquote>





	1. Recklessness

**Author's Note:**

> Disclaimer: I do not own Harry Potter and Sherlock Holmes, nor their characters.  
> English is not my first language, so if you notice any mistake please let me know.  
> Also, this is my first fanfiction, and any kind of comment or feedback would be greatly appreciated.  
> I hope you enjoy this :)

Reckless, brave, loyal. That sort of summed it up, according to many. Others would agree only with the first adjective and what he was about to do would definitely confirm their beliefs. Still, it was the only way he could think of to turn the tables and after twelve years surrounded by Dementors, two on the run and a whole summer imprisoned in a house he hated, he was more than ready to leap at the chance to do it. He closed the book he was pretending to read with a final thud and stood up. Remus opened his eyes a bit and watched him go from his position on the coach. He frowned and stared at the empty chair Sirius had been sitting on and then, with a small sigh, he returned to his sleep. After all, there was nothing he could possibly do after such a terrible full moon. 

In the meantime, Sirius had managed to retrieve all the muggle newspapers he had piled up in his father’s study. Heavily protected by spells, of course: he couldn’t let anything ruin his only plan. After rummaging for a few minutes, he finally found the one he was interested in. On the front page stood a blurred image of a man wearing a weird hat, probably a deerstalker, and the title read Sherlock Holmes Strikes Again. After the short summary of a crime well solved, the journalist had decided to write down everything they had managed to find out about the private life of the so-called Consulting Detective. And there stood also the address Sirius was looking for. 221B Baker Street, first floor. He seemed lost in thought for a moment but then his expression cleared and he quickly turned into a black dog.

Looking quite pleased with himself, he ran purposefully out. He was so single-minded and overwhelmed by the strength of his renewed hope that he didn’t even notice the front door slamming loudly behind him and the string of curses uttered by his mother’s portrait. But, most importantly, he didn’t feel the accusing eyes of his house-elf Kreacher on him. If he had, he would surely have seen the determined look and the wish to make its mistress proud. And he would have realized that leaving muggle newspapers out in a dark and gloomy house was definitely not a good idea. Right now, though, he was far more interested in the sun warming him up and in the happy faces he saw whenever he looked around. Not to mention the wonderful smells of London surrounding him and the amazing feeling of freedom.

After the initial happiness, though, he decided to slow down. What he was doing was already reckless enough and there was therefore no need to make it even worse by attracting unwanted attention. After all, there was a reason why he had to stay hidden and even if he didn’t like it he still had to recognize that it was safer to be protected by the magical wards of his much-hated house. So, while he continued to relish the fresh air and the possibility to stretch his legs… well, paws, he started to pay more attention to his surroundings, looking for the address with a care and resolution that would have surely made the passer-byes suspicious if they had looked at him twice. But that, thankfully, was what people did: they looked around without really seeing anything, not caring enough to actually pay attention. 

Suddenly, a scream filled the air and he shook himself, trying to dispel the need to look around frantically to find out what was going on in favour of keep pretending to be a normal dog. Still, he paid even more attention than before, grateful for the enhanced hearing his Animagus form gave him, and managed to catch a few irritated words from the voice that had screamed. He was still struggling to make sense of words such as bathtub, chicken, lung and clean when a door slammed shut. He jumped, noticing that it was the one directly on his right, and saw a man with blondish short hair stamping out. But, most importantly, he caught a glimpse of the number on the door: 221B.

His plan was a simple one: he had to get into the house, manage to get the attention of the detective and transform in front of his eyes. Of course, there were a lot of risks involved, starting from the fact that he was still wanted and even Muggles were aware of it, so there was no way it could have escaped the detective’s notice, and ending with him deliberately breaking the Statute of Secrecy. But it was worth it, as he repeated himself multiple times before going closer to the house and starting to scratch the door. It was a woman who opened the door, looking at him with a curious but nice expression but he didn’t give her time to sort out her thoughts and start thinking where he could have come from. He just run upstairs as fast as he could and got through the thankfully open door of what seemed to be a kitchen but was full of phials and laboratory equipment that make him stagger for a second. 

He had been having problems with memories since he escaped Azkaban: sometimes it was difficult to remember details of his life before, other times he was overwhelmed by them and now, apparently, it was not going to be different. All his memories of Potions came back to him, with those of the pranks he had come up with together with James, Remus and the traitor and a hundred emotions swirled in his head, making him strangely light-headed. And then, a man entered the kitchen. He was tall and had dark hair too, even if his were shorter and slightly more curled, and was frowning at him.

The man had just opened his mouth, probably to shout for the woman who opened the door, when Sirius transformed. He watched the eyes of the man widen as he took him in and then blink multiple times to hide his emotions. Afraid he would waste his only chance to explain, he started talking at once. Short and clear sentences, that was what he planned. This Sherlock Holmes was said to be the most logical person on Earth, so telling him facts was probably the only way to catch his attention.

“My name is Sirius Black. I’m a wizard and I can do magic. The proof is in front of your eyes: I was a dog, and now I am a man. I was wrongfully accused and imprisoned for the murder of my best friends and a dozen others twelve years ago. I escaped two years ago and I’ve been on the run ever since. I didn’t do it and I know who did, but he’s pretending to be dead so I can’t prove it. I’ve read you’re one of the best at what you do and I need your help. Will you take my case?”  
The other man was still staring at him, mouth slightly open and eyes blinking every few seconds. The silence went on for ages, and Sirius began to think that maybe saying everything so bluntly hadn’t been his best idea but, again, he was known for his recklessness. Then, when he was very close to decide whether he should just give up or shake the detective to make him realize the importance of this, he spoke.  
“The best”  
It was Sirius’s turn to stare at him uncomprehending.  
“What?”  
“I’m the best at what I do, not one of the best. Do sit down, this seems interesting.”


	2. Logic

It was a normal morning. The slightly damp air of mid October made a pleasant contrast with the surprisingly warm sun, the birds were still chirping loud enough to be heard over the typical noise of the traffic in a common working day in London and, all in all, the day promised to be quiet, peaceful and rather eventless. A heartfelt sigh arose from a black and comfortable-looking chair. Oh, scratch that, it was just going to be another boring, dull and predictable day.

The man sprawled on the chair jumped up at the sound of the door upstairs opening. At least, now that his flatmate was awake, he could be properly entertained. The foolishness and obviousness of his flatmate’s remarks and thoughts weren’t exactly stimulating, but he couldn’t deny that it was relatively enjoyable to have someone there to listen to him and recognize how smart he was. He heard the heavy footsteps coming closer and couldn’t help noticing a poorly concealed hesitancy in them. He frowned, trying to deduce the reason behind it and it took him a while to realize that it wasn’t the first time that it happened. Narrowing his eyes, he hummed at John’s “ ’Morning”. 

The other man’s blondish hair was slightly ruffed from his sleep and he had pillow lines on the left side of his face. The bags under his eyes were nothing new but seemed to be there to accuse him of not letting him sleep enough. Nothing unusual there. He had a day-old stubble he was going to take care of straight away, judging by the way he was scratching his chin absent-mindedly. The shirt he was wearing was one he normally used when he didn’t have to work and wasn’t going out on a date, so he didn’t hesitate out of fear of leaving him home alone. 

He was so caught up in his musings that it took him longer than he was willing to admit to understand the reason for the scream. John was in the bathroom, and he was sure that no criminal or client had managed to get in the flat undetected. As a matter of fact, he would have appreciated the distraction, but he had been in the bathroom earlier and he was sure that… Oh, right, the experiment. It had turned out to be completely useless, so he had deleted it, of course. But that could explain John’s hesitancy: he knew he had been working on something last night and was worried about the results. Understandable, if one chose to consider the more practical aspects of his experiments, as John usually did.

What he couldn’t understand was why the other man seemed so disgusted by the small amount of blood he had left in the bathtub. He was a doctor, after all, so he should be able to be logical, scientific and detached in front of parts of the body. So what if he had needed to add some leftover chicken to the punctured lung he had nicked from the morgue? That seemed the easiest way to test his theory and it was only unfortunate that the balance of probability had turned out to be incorrect. 

John, though, didn’t seem to agree with his feeble protests and he knew better than to start arguing with the army doctor when he sounded so angry. After all, he had a gun upstairs and he definitely knew how to use it. So he silently listened to the lecture and eventually to the door slamming as his flatmate stamped out of the house. Well, that could have gone better. Sighing, he decided to check the bathtub. Mrs Hudson had probably heard everything and there was a limit to what the landlady was willing to clean, or put up with, just because he had managed to have her husband executed. 

When he had almost reached the door, though, he heard a strange noise. Someone, or something, was running up the stairs. Four legs, definitely an animal then. He heard the creature entering the flat and coming to a sudden halt in the kitchen. Curious, he decided to go and investigate. It wasn’t every day that a largely sized animal decided to come to his flat, and lost or abandoned animals were definitely not that resolute. The sight in front of him, though, was definitely not what he had expected. It was a dog, a huge black dog that for a moment brought up memories of hounds and genetic mutations that he had tried to delete, apparently unsuccessfully. But, even weirder was the expression on the dog’s face. Because yes, there was definitely an expression there, and a human-like one in that. Emotions were not his area, so finding himself in front of a dog that expressed them left him speechless. It took the dog a while to compose itself but when it did it seemed to notice him and react accordingly. He stopped thinking altogether when he saw the dog turning into a man in front of his eyes. 

Now, Sherlock Holmes had seen many weird things during his life and enjoyed giving a logical explanation to every single one of them. Everything had a cause, everything happened as a logical consequence of something else and there was no way he was going to change his beliefs just because something didn’t make any sense whatsoever. And then, even more surprisingly, the dog-man spoke.

“My name is Sirius Black. I’m a wizard and I can do magic. The proof is in front of your eyes: I was a dog, and now I am a man. I was wrongfully accused and imprisoned for the murder of my best friends and a dozen others twelve years ago. I escaped two years ago and I’ve been on the run ever since. I didn’t do it and I know who did, but he’s pretending to be dead so I can’t prove it. I’ve read you’re one of the best at what you do and I need your help. Will you take my case?”

That made it. Sherlock Holmes, the most logical person in the whole world - not considering his brother, obviously- was this far from losing it completely, apparently. The man in front of him was real, of that he had no doubt. He was malnourished, worn and desperate, with recently cut hair that were frankly still too long, and old-fashioned clothes that hung on his too thin frame. He had never seen anyone quite like him in his whole life, so there was no way he could be making him up. He wasn’t hallucinating either: he didn’t have a fever, let alone a fever high enough for him to be hallucinating, and he wasn’t… well, the other alternative was out of bounds with a careful doctor as a flatmate. 

Now, it could be a trick. John seemed the obvious perpetrator, as he seemed to enjoy far too much the rare occasions when he got to see him losing his control to do something extremely mundane and human. However, he had just left looking rather angry, and he couldn’t have come up with this idea with such a short notice. He could have planned it all ahead, obviously, and then forgotten about it. This could explain the unconscious hesitation in his pace. And yet, it was far more elaborate a trick than John could hope to arrange. That left Mycroft. It was always Mycroft. The fact that he had chosen a dog seemed to confirm his suspicion. He always used Redbeard to prove his superiority, showing that caring was a mistake he had never made, unlike his baby brother. And bringing up the hound and Baskerville- the last time he had clearly needed his power- was just one more hint. 

But was a trick really possible? This was his flat, there was nothing weird in it and definitely nothing that could make him see something that wasn’t really happening. No mirrors in the kitchen, no lamps that could be used to deceive him, nothing out of the ordinary. So what now? If you eliminate the impossible, whatever remains, however improbable, must be the truth. That had always been his answer, but could he use it now as well? That meant admitting that magic existed, that the man in front of him had actually been a dog before turning into a man, that he wasn’t lying to him just to get his attention but really meant what he said. Which, by the way, seemed a very promising case. Definitely unlike anything he had heard before. 

That made it. He was bored after all, and there was nothing like an interesting case to keep the boredom at bay, especially without John around. He quickly pointed out the only mistake he was in the position to rectify, clearly stating that he was the best, not just one of the best, before asking the man to sit down. He sighed in exasperation when the man didn’t move. He really couldn’t understand why people never seemed to be able to keep up. And this was just a simple request, not even an intricate and brilliant deduction to take in. He firmly repeated himself, gesturing invitingly towards the living room and eventually the man seemed to understand what was expected of him and complied, sitting down gingerly on John’s chair. 

In the meantime, he decided that some tea would be greatly needed and, after checking the kettle with a hopeful expression that quickly turned disappointed, he shouted for Mrs Hudson to bring up some. He quickly examined the room to make sure there were no cameras around before doing the same in the living room and relaxing visibly when none was found. Definitely not a trick from his brother then, good. Mrs Hudson chose that moment to enter, bringing a tray with two cups of tea- apparently she was planning to drink hers there and casually bring up the bathtub- and some freshly baked Bakewell tarts. She came to a halt at the sight of the man sitting in John’s chair and he could see her going through the possibilities with painful slowness. He easily ushered her out before sitting down on his own chair.

Crossing his legs and making himself comfortable, he gestured vaguely to the tea, waiting for the man to select one of the cups before picking up the other. He sipped at it absent-mindedly, keeping his eyes firmly on the man, who appeared to be deep in thought. The frown and slight trembling of his hands were enough to deduce that he hadn’t expected it to go this way. Apparently, he had prepared a speech to explain what he wanted to say in the best possible way but hadn’t considered what may happen after that. A man that didn’t think ahead then, probably reckless since he was in the flat of a detective after escaping from prison without any kind of backup plan. If he decided to believe that the man had told the true, the years spent on the run could explain his worn-out aspect, but the malnourishment went beyond that. Probably a prison that didn’t abide by the standard rules, then. And the desperate look was not just desperation to be heard and believed, it went deeper than that, probably torture -psychological torture, since he didn’t seem to have glaring or prominent scars- and depression. Clothes and haircut, however, seemed to indicate that he was currently living somewhere safe and protected, but his paleness revealed that he was not allowed out. London then, with noisy neighbours that would have recognized him if he decided to leave the house and no backyard garden. 

Of course, if the man could actually turn into a dog he could go out for a walk whenever he liked without being recognized. Still, he clearly didn’t know enough about mysterious transformation to be able to make deductions on that. Taking a deep breath, he asked the man to start from the beginning and tell him everything that could be relevant to the case: data, facts, the like, and, obviously, everything he knew about magic. Then, he sat down more comfortably, waiting for what was surely going to be a juicy story to start.


End file.
